A Bird Blog with Kate St. John

Archive for October, 2013

This nocturnal member of the weasel family isn’t found in Pennsylvania but occurs from western Ohio to the California coast. He makes a living by digging for small burrowing animals, especially mice, squirrels and prairie dogs so his favorite places are grasslands where the soil is easy to dig and his prey is abundant. That’s a habitat rarely found in Pennsylvania.

American badgers are nature’s backhoes but they work at night and are usually alone. This makes them hard to watch and census. Even so, we can guess they’ve declined or are missing from areas where prairie dogs have been eradicated.

Leaf roosting has made him unusual in other ways, too. Most bats roost head-down but this species roosts head-up so it can exit the leaves quickly. Leaves are smooth and slippery so the bat has evolved suction cups on his wings and feet. These cups look like disks, hence his name.

Above, the bat is showing off his wing disks but his arms look really weird and stubby. To understand this it helps to know a little about bat-wing anatomy.

Bats’ wings are made of skin stretched from their armpits to their fingertips. Their four fingers, encased in thin skin, have evolved to be very long to give the wings their breadth. Bats’ thumbs, however, are not inside their wings and their thumbs are short.

In the photo above you can see the attic bats’ long fingers. The joint of the wing is at the bat’s hand/wrist. I’ve circled the tiny thumb. This one has a claw but Spix’s disk-winged bats have a suction-cup there instead.

When bats roost, they close their fingers to fold their wings. Most bats grab a perch with their feet but Spix’s uses suction cups to latch onto the inside of the leaf.

Suction cups on his feet alone are not enough. This bat is hanging on by his thumbs.

(photo of a Spix’s disk-winged bat taken near Golfo Ducle, Costa Rica by Alan Wolf. Bat wing from Wikimedia Commons. Click on each photo to see the original.)

Here’s an amazing fact: Among birds, and especially among declining species, there are more males than females.

It’s always easier to find male birds during breeding bird surveys. They’re clothed in conspicuous colors and put on a big show, singing and displaying to claim territory and find a mate. Females are hard to see because they don’t sing, are often cryptically colored, and are secretive around the nest. Unfortunately it’s not just flashiness that makes males easier to count. The males are saying “Notice me!” because there aren’t enough females to go around.

Why does this happen? Dr. Donald explained, “It’s not that females are producing more sons than daughters, because at hatching the sex ratio is generally equal. The only possible explanation is that females do not live as long as males. As generations grow older, they become increasingly dominated by males as more females die off.”

Dr. Donald also found that the skewed sex ratio is even worse among endangered birds and at its worst among the rarest species. He hypothesized this is due to predation of females while on the nest — the double whammy of killing current and future generations at the same time.

The City of Pittsburgh is outside the summer tanagers’ range so it was quite rare that I found a pair of summer tanagers breeding in Schenley Park in 2011. I noticed them just after their nest failed (due to a predator) because the male was impossible to ignore. He was so angry he was shouting at everyone.

He and his lady tried for a second nest but it was too late in the season and they dispersed without success. The next spring he was back again and easy to see. He called and displayed, sang and sang, but she never showed up. He was alone and that made it much easier for everyone to find him. In 2012 he never had a mate.

This year he didn’t show up at all. I assume both he and his lady have died.

Fortunately summer tanagers have a very wide range and their population is doing well — they are listed as “Least Concern” — but they illustrated Dr. Donald’s finding: Among most bird species there are more males than females.

I remember these little red fruits from my childhood. I used to pick the berries along my walk to elementary school and roll them between my fingers. Firm, shiny, and somehow soothing.

Japanese barberry (Berberis thunbergii) is a pretty plant which forms a thorny border that discourages kids and dogs from entering one’s yard. For this and other reasons it was introduced to the U.S. in 1875. Unfortunately by now Berberis thunbergii and its European cousin (Berberis vulgaris) have overtaken our native barberry (Berberis canadensis) and become invasive.

Japanese barberry has a secret advantage over Pennsylvania’s native plants. Deer won’t eat it so it easily forms dense, thorny thickets. But don’t plant it! It’s a tick magnet.

Studies by the Connecticut Agricultural Experiment Station in Lyme, Connecticut discovered a strong link between dense Japanese barberry thickets and Lyme disease. Deer ticks prefer these thickets for their cool, moist microclimate. White-footed mice hang out in the thickets because the larger predators can’t reach them there. White-footed mice are the main carriers of Lyme disease bacteria. The ticks bite the mice and voilà! Lots of Lyme disease.

The Adirondack Daily Enterprise wrote of this study: “Deer ticks are 67 percent more likely to be in areas infested with barberry than those areas that have native plants, and a higher percentage of ticks in infested areas carry the Lyme bacteria than those in areas that are barberry-free – 126 infected ticks per acre versus 10 per acre. When managers removed barberry plants, the number of ticks dropped up to 80 percent – a compelling outcome.”

So if you want to find deer ticks and Lyme disease, bushwhack through a barberry thicket.

The plant in this photograph was alone, growing by the side of a rail trail, but I found a tick on my pants after I took the photo.

The big round balls, which cradle easily in the palm of my hand, are husk-covered nuts. They’re green when ripe but turn brown with age (bottom right). Their four sections naturally come open as the nut ages and sometimes burst when they hit the ground.

I didn’t need any special tools to open the husks, just my fingers. At first I didn’t realize they were merely husks so I thought it was odd that they didn’t protect the nut but…

The nutshell is another story (center of the photo). Irregularly shaped and slightly larger than a quarter, I tried to open it by cutting and other gentle means but it was impossible. The meat inside is reputed to be sweet but I had to destroy the nut to taste it.

Hmmm. Get out a hammer or hire a squirrel.

I got out the hammer.

The first nut had very shriveled meat inside. Perhaps it had been attacked by a bug.

The second and third nuts looked promising except that the meats resembled dried Chinese wood ear mushrooms and they tasted like nothing. (My photo doesn’t do this justice.)

Either I was doing something wrong — quite possible — or these nuts are not as good as described.

I wonder how many nuts the squirrels spend time opening only to find that the meat inside was not worth it.

The pest is easy to recognize by its white egg sacs that cling to the underside of the branches. They kill hemlocks by sucking the juice out of the needles. Infected trees look gray-green instead of deep green and, under a heavy infestation like the one shown above, can die in only four years. This is sad anywhere but especially unfortunate in Cooks Forest where the old growth hemlocks are over 300 years old.

It has taken a long time for the bug to reach Cooks Forest. HWA arrived from Asia in 1924 but moved very slowly across the eastern U.S. By 2007 it was present in 50% of the eastern hemlock’s range, unable to spread far northward because of harsh winters. Unfortunately our climate is warming so new adelgid territory opens up every year. (Notice on this NOAA plant hardiness map that the location of Cooks Forest warmed enough to change growing zones.)

HWA was first spotted in eastern Pennsylvania in 1967 but took about four decades to cross the Allegheny Front into western PA. Slowly, slowly it crept toward Cooks Forest. By 2010 it was in the vicinity. This year it was there.

Knowing the imminent danger DCNR has treated the area and the old growth trees. They use biological controls — Asian beetles that eat adelgids, though not enough of them — and soil or bole-injected insecticides on specific trees. The poisons are systemic, similar in concept to the insecticide treatments for emerald ash borer that kill or repel all insects. The treated trees will have fewer insects living on them. Will this make them less useful to birds?

The question hardly matters. Nature can’t produce a 300 year old hemlock as fast as the adelgids can destroy one. In the case of our oldest treasures our task is clear. Save these trees if we can.

For more information on the hemlock woolly adelgid, click here for DCNR’s report.

(photo via Wikimedia Commons by Nicholas A. Tonelli at Jacobsburg, Northampton County, PA. Click on the image to see the original)

p.s. Thanks to Kim Getz for alerting me to this news. Because of the adelgids activity cycle, DCNR treated the old-growth trees in May and again in October.

Sandhill cranes are much more common out west but the eastern population has grown to 60,000 birds. They used to be rare in Pennsylvania where our first crane was noted in the late 1980’s, first breeding was recorded in 1993 in Lawrence County, and the first photograph of a nest was in 2009. Sandhills have now been spotted in more 30 Pennsylvania counties — nearly half the state!

This is your opportunity to make history. Put your name, location, count, date and time on record. It’s significant if you visit a likely crane place and don’t find any. Yes, even ZERO counts.

Where to count: Look for cranes in wetlands and nearby agricultural settings. Cranes often forage in shallows and mud flats along lakes, ponds, and swamps or in nearby agricultural fields and pastures, but they can be found in a variety of odd sites during migration. (Pittsburgh birders: visit Lawrence, Mercer, Crawford counties)

When: Sunday, October 27 through Saturday, November 2. Ideal dates are October 29-31. Counts are best conducted just after sunrise or just before sunset when birds are concentrated in their roost sites. (It’s easier to find cranes at that time of day, anyway.)

Anne Marie said, “Saw a murder of crows at the playground across the street from the Church Brew Works last night and a coworker saw them this morning in Schenley! Borrowed from Thin Lizzy (source: http://www.lyricsondemand.com/)

The crows are back in town! The crows are back in town!

Guess who just got back today?
Them wild-eyed crows that had been away
Haven’t changed, haven’t much to say
But man, I still think them cats are crazy.”

Silence isn’t their strong suit. The crows will have lots to say in the days ahead.

Let me know when you see them.

(photo from Wikimedia Commons. Click on the image to see the original)

If you’ve ever had a pet starling, you know their beaks are very powerful when opening. That’s because European starlings have the unusual characteristic that their jaws are strongest in reverse.

It’s a counter-intuitive trait. Our jaws are strongest when we clamp down. William Beecher discovered that starlings’ jaw muscles are at their best when they spring open and that their eyes automatically rotate forward for binocular vision as they open their beaks. This gives them an excellent look at potential prey in the hole they’ve just probed open and probably contributes to their success in winter.

Even as pets, starlings can’t help but probe. It’s in their blood. HayleyM‘s pet starling, Lolly, opens her son Aidan’s mouth as a dentist might. Notice that beak action!

Don’t try this at home!

Click here to view the original video and read in the comments how this orphaned starling became a pet. Also read the important notes in the p.s. below.

* In North America, European starlings are one of only two wild birds (the other being the house sparrow) that can be kept as pets without a permit. Both species are listed as invasive.

* In addition to the possibility of people catching disease from birds, HayleyM added this note to the video: “After review by my good friends at Starling Talk (www.starlingtalk.net), I have found out that this is an ill advised practice. Apparently the bacteria in the human mouth can actually make a bird sick.”